This is a supplement to a previously awarded grant with the same title. The clinical profiles of several developmental disorders, including autism spectrum disorders (ASD), involve varying degrees of co-occurring language impairment (LI). The underlying neuronal deficits for LI are numerous and may include deficits in perception, processing, and/or cognition. Current understanding of how a deficit at each or any of these levels might relate to LI is not sufficiently sophisticated to distinguish neuronally-based subtypes of LI. In this study, researchers seek to identify electrophysiological signatures, or endophenotypes, associated with the neural correlates of language impairment in ASD. Specifically, a population of children with autism spectrum disorders (both with and without concomitant LI) will be investigated to find neuronal characteristics associated with autism per se, with LI per se, and with both in combination. If endophenotypes to language impairment can be found, individuals could be sub-typed, or grouped together by the nature of their underlying neuronal deficit, which may aid greatly in addressing the heterogeneity of ASD and in the design of future interventions appropriately targeted to varying ASD subtypes.